The primary objective of the National Surgical Adjuvant Project for Breast and Bowel Cancers (NSABP) is to produce reliable, statistically significant data relative to the natural history of breast, and, more recently, bowel cancers. The method employed in thefulfillment of this objective is that of well-designed, sequential protocols applied to the large patient population generated by the 104 member institutions. As a participating institution, the University of Iowa has contributed to patient accrual in Protocols #B-04, #B-07, #B-08, #B-09, #B-10, #B-11, and #B-12. Quality follow-up has been maintained on all patients randomized to these protocols. Our multidisciplinary approach and strict compliance with protocol requirements enhance the overall group objectives. Our ten years of experience with the clinical trials of this cooperative group, coupled with a major reorganization designed to yield increased patient accrual provide the framework for a major contribution to future NSABP endeavors. The current application seeks funding to permit: (1) Continued patient accrual in ongoing protocols, and in future NSABP protocols. (2) Strict and prolonged follow-up on all protocol patients; (3) Collection of appropriate biological materials and information relevant to these protocols; (4) Education through dissemination of information and participation in cooperative clinical trials by community physicians throughout the state.